Which of the following has the highest dipole moment?

Which out of $NH_{3}$ and $NF_{3}$ has a higher dipole moment and why?

Which of the following arrangements of molecules is correct with respect to their dipole moment?

Which of the following is the correct order of dipole moment?

The dipole-dipole interaction energy between polar molecules in the solid state will be proportional to ...... [if $r$ denotes the distance between polar molecules]

$H_2O$ is polar while $BeF_2$ is not. The reason for this is ...